1. Field of the Invention
The present invention relates to semiconductor devices capable of communication with the use of contactless means such as wireless communication, and a manufacturing method thereof. In particular, the present invention relates to a semiconductor device that is formed over an insulating substrate of glass, plastic, or the like and a manufacturing method thereof.
2. Description of the Related Art
With development of computer technologies and improvement of image recognition technologies, data identification methods utilizing a medium such as bar codes have spread widely and have been used for identification of product data and the like. It is expected that the amount of data to be identified will further increase in the future. On the other hand, data identification utilizing bar codes is disadvantageous in that a bar code reader is required to be in contact with the bar codes, and that the amount of data capable of being stored in the bar codes is small. Therefore, contactless data identification and increase in the storage capacity of a medium are required.
In view of the foregoing requirements, a semiconductor device capable of wireless communication with the use of an IC (also referred to as an ID chip, an IC chip, an IC tag, an ID tag, a wireless chip, or an RFID) has been developed recently. The data is stored in a memory circuit in the IC in the semiconductor device and is read by contactless means, generally wireless means. It is expected that practical application of such a semiconductor device will allow commercial distribution and the like to be simplified and made cheaper while ensuring high security.
An overview of an individual recognition system using the above-described semiconductor device capable of wireless communication with the use of an IC is described with reference to FIG. 2, FIG. 3, and FIGS. 4A and 4B. FIG. 2 illustrates an overview of an individual recognition system for obtaining individual data on a bag without contact.
A semiconductor device 221 storing particular individual data is attached to or embedded in a bag 224. A signal is transmitted to the semiconductor device 221 from an antenna unit 222 which is electrically connected to an interrogator (also referred to as a reader/writer) 223. When receiving the signal, the semiconductor device 221 sends back the individual data that the semiconductor device holds to the antenna unit 222. The antenna unit 222 sends the individual data to the interrogator 223, and the interrogator 223 identifies the individual data. In this manner, the interrogator 223 can obtain the individual data on the bag 224. Furthermore, this system enables physical distribution management, counting, exclusion of a counterfeits, and the like.
For example, such a semiconductor device has a structure shown in FIG. 3. A semiconductor device 200 includes an antenna circuit 201, a rectifier circuit 202, a stabilizing power supply circuit 203, an amplifier 208, a demodulation circuit 213, a logic circuit 209, a memory control circuit 212, a memory circuit 211, a logic circuit 207, an amplifier 206, and a modulation circuit 205.
For example, the antenna circuit 201 includes an antenna coil 241 and a capacitor 242 (FIG. 4A). For example, the rectifier circuit 202 includes diodes 243 and 244 and a capacitor 245 (FIG. 4B).
An operation of such a semiconductor device 200 capable of wireless communication with the use of an IC is described below. A wireless signal received by the antenna circuit 201 is half-wave rectified by the diodes 243 and 244 and then smoothed by the capacitor 245. The smoothed voltage containing a plurality of ripples is stabilized by the stabilizing power supply circuit 203, and the stabilized voltage is supplied to the demodulation circuit 213, the modulation circuit 205, the amplifier 206, the logic circuit 207, the amplifier 208, the logic circuit 209, the memory circuit 211, and the memory control circuit 212.
Moreover, a signal received by the antenna circuit 201 is input to the logic circuit 209 as a clock signal through the amplifier 208. Further, a signal input from the antenna coil 241 is demodulated by the demodulation circuit 213 and input as data to the logic circuit 209.
In the logic circuit 209, the input data is decoded. Since the interrogator 223 sends data after having encoded it, the logic circuit 209 decodes the data. The decoded data is sent to the memory control circuit 212, and then data stored in the memory circuit 211 is read out.
It is necessary that the memory circuit 211 be a nonvolatile memory circuit which is capable of storing data even when the power is OFF, and a ROM (Read Only Memory), or the like is employed (Japanese Patent No. 3578057).
As a transmitted/received signal, 125 kHz, 13.56 MHz, 915 MHz, 2.45 GHz, or the like may be employed, to each of which the ISO standard or the like is applied. In addition, a standard is also set for a modulation and demodulation system in transmission/reception.
In order to manufacture the above-described semiconductor device capable of wireless communication with the use of an IC, in a nonvolatile memory circuit, for example, a mask ROM has been necessarily formed as described above.
However, the mask ROM (hereinafter simply referred to as a ROM) can only write data at the time of manufacturing. Therefore, data is written at the same time as the manufacture of the mask ROM in manufacturing the semiconductor device.
Individual data of an individual semiconductor device such as an ID number is stored in a ROM. The individual data such as the ID number varies between individual semiconductor devices. However, since the ROM is generally manufactured by photolithography, in order to vary the individual data such as the ID number between the individual semiconductor devices, a photomask has to be formed for every one of them. Thus, when the individual data such as the ID numbers are formed to be all different, a heavy burden is imposed on manufacturing cost and the manufacturing process.
Therefore, in manufacturing a semiconductor device like this, there is a method for forming data in a ROM with a laser direct drawing apparatus (also referred to as a laser light exposure direct drawing apparatus), an electron beam direct drawing apparatus (also referred to as an electron light exposure direct drawing apparatus or an electron beam light exposure apparatus), or the like instead of using photolithography. When a semiconductor device is manufactured with any of these direct drawing apparatuses or the like, it becomes easy to vary individual data such as an ID number written to individual semiconductor devices.
However, the method for manufacturing the semiconductor device with the laser direct drawing apparatus, an electron beam direct drawing apparatus, or the like is less precise than a method using photolithography. In addition, when the laser direct drawing apparatus, the electron beam direct drawing apparatus, or the like is used, there is a possibility that a manufactured semiconductor device may not match the design rule.
In consideration of such a situation, the present invention provides a semiconductor device, and a method of manufacturing the semiconductor device, capable of wireless communication with the use of ICs, in which each semiconductor device comprises a ROM including individual data, such as an ID number, different from the individual data of another semiconductor device.